A remote terminal unit (RTU) represents a device or system that provides localized control and data access at a site that is remote from a supervisory control and data acquisition (SCADA) system or other automation system. For example, multiple RTUs can be used at different sites and for different purposes in an oil and gas field. The RTUs can collect data, perform local control, record historical values using sensors and actuators at different sites (such as wells, pipelines, and compression stations), and provide live and historical data to a SCADA system. The SCADA system can execute control logic and alter the operations of actuators at the different sites via the RTUs. The RTUs themselves could also incorporate algorithms for data analytics.
The remote terminal unit (RTU) may include several serial communication connections to communicate with the SCADA system and one or more field devices. The rapid development of drilling for shale gas has caused oil and gas projects to require more input/output (I/O) ports. Generally, the RTU is deployed in the field; low bandwidth communication is a limitation of many oil and gas projects. When parameters are not configured properly, low baud rate communication may cause a serial communication timeout in many industry projects that are restricted by a low bandwidth channel. For example, a timeout parameter may be configured to be too short, and the RTU determines that an end time of the timeout wait period has occurred prior to receiving a response from a field device, which is an indicator that no connection is established between the RTU and the field device. Though the RTU can retry to connect by sending a subsequent request, the too short timeout wait period causes the same result, indicating that a connection cannot be established with the field device. Without a connection with the field device, such as a pressure sensor, the RTU cannot receive pressure sensor measurements from the field device in order to forward them to a user.